It is well known to feed combustion chambers for turbine generator boilers with airborne particulate coal; structures for carrying out this function are commonly found in electric utility plants throughout the United States and Canada. It is common in these systems to use a main supply conduit to receive particulate coal from a pulverizer/classifier. It is also common to divide the main supply conduit into several parallel branches which are connected to spaced points around the combustion chamber.
A problem which arises in systems of the type described above is ensuring that the branch conduits exhibit at least approximately equal coal flow rates so that the fireball in the combustion chamber is stabilized as to size and location within the combustion chamber. The flow of particulate coal through parallel branch conduits of different lengths and configurations tends to be unstable and inherently non-uniform. Many devices have been created to deal with this problem; see, for example, U.S. Pat. Nos. 5,873,156, 6,055,914, 6,186,079, 6,257,415 and 6,234,090.